• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1419-1435
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• 2015

In this study an active RFID system of low power consumption is proposed, for which we improved the tag collection algorithm of ISO/IEC 18000-7 standard and significantly reduced the tag collection time. We classified the type of power consumption according to the operating mode of active RFID and proposed the method which can accurately estimate battery life time. By calculating the power consumptions of proposed and current methods, we can compare the battery life times of both methods. Through this analysis we can demonstrate the superiority of the proposed method in battery life time.

• Annual Conference of KIPS
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• 2007.05a
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• pp.525-528
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• 2007

기존의 웹서비스가 정적이고 수동적인데 반해 최근의 웹 서비스는 점차 동적이고 능동적으로 변화하고 있다. 이러한 웹서비스 변화의 흐름을 잘 반영하는 것이 웹 2.0이다. 웹 2.0에서 대부분의 정보는 사용자에 의해 생산되고, 사용자가 붙인 태그(tag)에 의해 분류되어진다. 그러나 현재 태그에 관한 서비스 및 연구들은 태깅(tagging) 방법에 대한 연구를 비롯해 이를 표현하기 위한 tag cloud에 초점이 맞춰져 진행됨에 따라, 다양한 태그 정보자원 간의 체계와 연결 관계인 지식체계를 제공하지 못하고 있다. 이에 본 논문에서는 체계화된 지식표현을 위해 웹상에 편재되어 있는 학습 관련 리소스(resources) 및 태그들를 수집한다. 이를 사용자가 요청한 검색 키워드와 연관성이 있는 태그 정보들을 맵핑 및 클러스터링하여 최적화된 표현 형식인 토픽 맵(topic map)화하기 위한 시스템을 제안하며, 이 중 토픽 맵 생성을 위한 초기 연구 단계로서, 연관 태그들 간의 맵핑 및 클러스터링을 위한 알고리즘 제시를 중심으로 소개한다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.4
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• pp.311-317
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• 2011

Recently, RFID is substituted for bar codes according to advance in the ubiquitous computing environments, but the RFID system has several problems such as security and privacy because it uses radio frequencies. Firstly, unauthorized reader can easily read the ID information of any Tag. Secondly, Attacker can easily fake the legitimate reader using the collected Tag ID information,such as the any legitimate tag. This paper proposed improved RFID authentication protocol based on SSG. SSG is organized only one LFSR and selection logic. Thus SSG is suitable for implementation of hardware logic in system with extremely limited resources such as RFID tag and it has resistance to known various attacks because of output bit stream for the use as pseudorandom generator. The proposed protocol is secure and effective because it is based on SSG.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.415-421
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• 2005

Passive RFID tag does not have its own power, so it has very poor computation abilities and it can deliver signals in very short range. From the facts, most RFID Tag security schemes assumed that the backward channel from tags to a reader is safe from eavesdropping. However, eavesdroppers near a tag can overhear message from a tag illegally. In this paper, we propose a method to protect the backward channel from eavesdropping by illegal readers. The proposed scheme can overcome the problems of conventional schemes such as randomized tree walking, which have been proposed to secure tag information in tree-walking algorithm as an anti-collision scheme for RFID tags. We showed the efficiency of our proposed method by using an analytical model, and it is also shown that the proposed method can provide the probability of eavesdropping in some standardized RFID tag system such as EPCglobal, ISO, uCode near to '0'.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.8
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• pp.1569-1580
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• 2016

For the 2.4 GHz active RFID to be successful in the market, one of the requirements is the increased battery life. However, currently we do not have any accurate power consumption estimation method. In this study we develop a simulation model, which can be used to estimate power consumption of tag accurately. Six different simulation models are proposed depending on collision algorithm and query command method. To improve estimation accuracy, we classify tag operating modes as the wake-up receive, UHF receive, sleep timer, tag response, and sleep modes. Power consumption and operating time are identified according to the tag operating mode. Query command for simplifying collection and ack command procedure and newly developed collision control algorithm are used in the simulation. Other performance measures such as throughput, recognition time for multi-tags, tag recognition rate including power consumption are compared with those from the current standard ISO/IEC 18000-7.

• Journal of KIISE
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• v.43 no.10
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• pp.1173-1178
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• 2016

Since the introduction of BitTorrent protocol in 2001, everything can be downloaded through file sharing, including music, movies and software. As a result, the copyright holder suffers from illegal sharing of copyright content. In order to solve this problem, countries have enacted illegal share related law; and internet service providers block pirate sites. However, illegal sites such as pirate bay easily reopen the site by changing the domain name. Thus, we propose a technique to easily detect pirate sites that are reopened. This automated technique collects the domain names using the google search engine, and measures similarity using Longest Common Subsequence (LCS) algorithm by comparing the tag structure of the source web page and reopened web page. For evaluation, we colledted 2,383 domains from google search. Experimental results indicated detection of a total of 44 pirate sites for collected domains when applying LCS algorithm. In addition, this technique detected 23 pirate sites for 805 domains when applied to foreign pirate sites. This experiment facilitated easy detection of the reopened pirate sites using an automated detection system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.1
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• pp.41-49
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• 2007

RFID in which subminiature IC chip with the indentified information is built a core technique that can recognize, trace and manage various information of an object using radio frequency in the age of Ubiquitous. Several pressing matters about an infringement of Privacy and a security of private information should be settled as soon as possible because an information of specific circumstance can be collected and used without any awareness by others as well as a private information. In addition, various algorithms with high level of security, which is normally used in wire, can be hardly applied to RFID tag because of a lot of restrictions of tag. In this report, designed-RFID tag based on the standard of ISO/IEC 18000-6 and the problems which originated from the technical procedure of that design were analyzed, and the algorithm which could be applied to the designed-tag was also investigated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8B
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• pp.1028-1037
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• 2011

Recently, Selim et al proposed public key cryptography based privacy preserving multi-context RFID authentication protocol. However Selim et al's proposed protocol not only doesn't fit into passive tag based RFID system because it uses public key based encryption algorithm to perform authentication between reader and tag, but also is insecure to an impersonation attack because it doesn't provide mutual authentication. In order to eliminate the above described efficiency problem and security vulnerabilities, this paper proposes a new multi-context RFID mutual authentication protocol that can prevent privacy invasion and tag impersonation attack through providing mutual authentication between single passive tag which is located different application space and readers which provide multi-context purposes and can secure against relay attack and denial-of-service attack. As a result, the proposed protocol performs secure mutual authentication based on the collected space and time information from the RFID reader and provides strong security and high computation efficiency because if performs secure one-way hash function and symmetric encryption operations suitable to the environments of passive RFID tags.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.02a
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• pp.201-204
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• 2008

RFID의 무선을 통해 자동 인식 기술은 산업, 상업 그리고 의료 분야에 혁신적인 개선을 가져다 줄 것으로 기대되고 있다. RFID 기술의 핵심은 물리적인 물체에 관련한 정보를 쉽게 수집할 수 있다는 것이다. 미들웨어는 RFID 리더와 응용 사이에 위치하면서 RFID 정보를 실시간으로 수집하고 기업응용에 전달해주는 중요한 역할을 담당한다. 따라서 네트워크로부터의 공격이나 잘못된 명령으로부터 미들웨어를 보호하기 위해 적절한 접근제어가 필요하다. 본 논문은 RFID 미들웨어에 적용가능한 접근제어 정책을 제안한다. 이 정책은 제공가능한 태그 범위, 접근가능한 리더, 명령, 보고가 배달되어질 주소등을 제한할 수 있도록 고안되었다. 또한, 접근제어 정책을 수행하는 프로세스의 구현 알고리즘을 제시한다.

• Journal of KIISE:Software and Applications
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• v.30 no.5_6
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• pp.476-486
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• 2003

There is no explicit spelling change information in part-of-speech tagged corpora of Korean. It causes some difficulties in acquiring the data to study Korean morphology, i.e. automatically in constructing a dictionary for morphological analysis and systematically in collecting the phenomena of the spelling changes from the corpora. To solve this problem, this paper presents a method to recognize spelling changes between morphemes of a Korean word in tagged corpora, only using a string matching, without using a dictionary and phonological rules. This method not only has an ability to robustly recognize the spelling changes because it doesn't use any phonological rules, but also can be implemented with few cost. This method has been experimented with a large tagged corpus of Korean, and recognized the 100% of spelling changes in the corpus with accuracy.